Spark plugs fouling on Massey Ferguson MF 35 petrol gasoline 87mm Standard engine

[stephanadams]

Some have a couple of different options. vps germany Maybe carefully check by measuring to see how much room you have when a piston is a top dead center.

 

[Jerry/MT]

Hi,

I have a misfiring and spark plug fouling issue on my 1962 MF35 with the Standard Motor Co 87mm petrol (gasoline) engine. Please note this is not the Continental engine in the US market, but the UK petrol offering. The misfire is most noticeable at light load and nearly entirely stops when loaded/working at 1600 rpm. The plugs, NGK B6S, foul to the point of arcing down the insulator (in the combustion chamber, not the external insulator) causing them to fail to work. This has occurred on 2 cylinders and it is part, or possibly all, of the misfiring issue I have. The motor burns minimal to no oil, has suitable compression across all 4 cylinders. The tractor does around 5 short runs of light work each week, which do bring it to 60C (140F), but it only "works hard" around twice a year. Fuel is 91 octane and due to recent supply changes locally, I am hearing reports it burns dirty. I use a valve protection additive.

Questions:
1). anyone got a suggestion for resolving this plug fouling issue?
2). Would a "hotter" plug help burn the build up off the nose?
3). what brand/type of plug are people using in this motor?

Thanks in advance

What does the fouling look like? If it's oily, wet, black stuff, that's oil fouling. If it's black fluffy looking soot, that's a mixture issue or a cold plug.

Worn intake valve seals/worn valve guides will exhibit blue smoke at idle where manifold vacuum is maximum, and it will go away at high engine load when the vacuum is a minimum.

If you have oil fouling, then sometimes the inserts will help you get by but the long term fix is to attack the root cause...worn valve guides/worn seals. replace the seals and the valve guides or have the valve guides knurled.

If the fouling is a soot type, work on the mixture and go to a hotter plug. You should be using non-resistor plugs in these old machines.

 

[FordnMassey]

Hi,
Dry black soot, if I do light duties for several hours.
Interestingly, hard work for 6 hours and I have clean, toasted bread tan colour on all plugs. And the misfire is still there. So I'll pursue other causes of misfire.
I'll report back after I do some work on it.

 

[pmsmechanic]

How worn is your distributor shaft? That could be the cause of your low speed misfire. Take the cap off and check for sideways and up & down play. I don't know what the specs are but seems like about .010" vaguely rings a bell for a Chevy distributor.

 

[FordnMassey]

How worn is your distributor shaft? That could be the cause of your low speed misfire. Take the cap off and check for sideways and up & down play. I don't know what the specs are but seems like about .010" vaguely rings a bell for a Chevy distributor.

Hi,
The distributor bush (bottom) and bearing (top) were very bad and I replaced the top bearing about a year ago. I couldn't buy the bottom bush and would need to machine one, so I left it. Timing light showed a reduction in variation of timing from 12 degrees to 2 degrees, which in my experience is pretty normal (correct me if I'm wrong). The top of the shaft previously moved enough to nearly close the points, but after repair, it was 0.001-2". I reckon I resolved this as an issue.